[Mrumpiresir]

Originally Posted by Justme561

Rule 7.09 It is interference by a batter or a runner when—

(f) If, in the judgment of the umpire, a base runner willfully and deliberately interferes with a batted ball or a fielder in the act of fielding a batted ball with the obvious intent to break up a double play, the ball is dead. The umpire shall call the runner out for interference and also call out the batter-runner because of the action of his teammate. In no event may bases be run or runs scored because of such action by a runner.

(k) A fair ball touches him on fair territory before touching a fielder. If a fair ball goes through, or by, an infielder, and touches a runner immediately back of him, or touches the runner after having been deflected by a fielder, the umpire shall not declare the runner out for being touched by a batted ball. In making such decision the umpire must be convinced that the ball passed through, or by, the fielder, and that no other infielder had the chance to make a play on the ball. If, in the judgment of the umpire, the runner deliberately and intentionally kicks such a batted ball on which the infielder has missed a play, then the runner shall be called out for interference.
PENALTY FOR INTERFERENCE: The runner is out and the ball is dead.

You didn't supply the rule that applies to the OP. You would be correct in the case of a runner "willfully and deliberately" interfering with a batted ball or fielder. But the OP doesn't say this. So the ball is dead, the runner is out and the batter is awarded first base. The offensive coach was correct that the batter is not out.

Read rule 6.08(d).